Aim: The present study was planned to evaluate C-reactive protein and serum magnesium in preterm labor compared to healthy subjects. Introduction: Preterm labor is defined as the onset of labor before the completion of 37 weeks of gestation in a pregnancy beyond 20 weeks of gestation. Preterm is one of the leading causes of perinatal morbidity and mortality. It has approximately 70% of newborn deaths and 50% long-term neurological sequelae. The main cause of preterm labor is the preterm rupture of the membrane. In addition to that, there are some other risk factors too, such as multiple gestations, hypertension, anemia, cervical incompetence, prepartum hemorrhage, anomalies of fetus or uterine, heavy work, and smoking. Materials and methods: Fifty diagnosed preterm labor patients and 50 healthy subjects were enrolled for the study and subjected to analysis, including C-reactive protein and serum magnesium using Vitros 5600- Dry Chemistry Analyzer. Result: The present study reported significantly low levels of serum magnesium and higher levels of serum C-reactive protein in preterm labor patients when compared to healthy subjects. Conclusion: Findings of the present study suggest that serum C-reactive protein and serum magnesium levels can be used as a predicting tool of preterm labor.